Add FF for Registry group browser

This adds a feature flag to hide
and selective enable container registry
browser for some projects

app/controllers/groups/registry/repositories_controller.rb

@@ -4,6 +4,7 @@ module Groups
     class RepositoriesController < Groups::ApplicationController
       before_action :verify_container_registry_enabled!
       before_action :authorize_read_container_image!
+      before_action :feature_flag_group_container_registry_browser!
 
       def index
         track_event(:list_repositories)
@@ -22,6 +23,10 @@ module Groups
 
       private
 
+      def feature_flag_group_container_registry_browser!
+        render_404 unless Feature.enabled?(:group_container_registry_browser, group)
+      end
+
       def verify_container_registry_enabled!
         render_404 unless Gitlab.config.registry.enabled
       end

app/helpers/groups_helper.rb

@@ -22,7 +22,9 @@ module GroupsHelper
   end
 
   def group_container_registry_nav?
-    Gitlab.config.registry.enabled && can?(current_user, :read_container_image, @group)
+    Gitlab.config.registry.enabled &&
+      can?(current_user, :read_container_image, @group) &&
+      Feature.enabled?(:group_container_registry_browser, @group)
   end
 
   def group_sidebar_links